Windmills have been in use for many hundreds of years and they have been used to harness the energy of the wind to perform numerous task. For instance, windmills have been used to grind grain, operate pumps and other machinery and more recently in the earlier portion of this century to generate electric power. Many farms in this country used windmills to generate electricity to light lamps before electric powder was widely available.
Unfortunately, the windmills which were in use on farms were inefficient and gave something less than entirely satisfactory results. Consequently, as soon as electric power from central generating plants became available such windmills were no longer used to generate electricity and there appeared to be little future for electricity generating windmills.
The current threat of an energy crisis has caused a search for additional sources of electrical power and as a consequence the possibility of generating electrical power through the use of windmills is being re-examined. As it turns out, the advances which have been made in aerodynamics in recent years can possibly greatly improve the efficiency of windmills and permit them to be used as an economical source of electrical power.
One of the major problems associated with using windmills to generate electricity is the problem of wind drag loads on the windmill blades. These loads severely limit the structural efficiency of a windmill electric generating system and they increase with increasing revolutions per minute, r.p.m., of the windmill blades. In the past, these undesirable effects of wind drag have been reduced by varying the blade pitch angle at the root of the blade, in a manner similar to aircraft propellers, through the use of complicated and expensive rotor hub assemblies which vary the pitch angle of the entire windmill blade.
Through the use of this invention it is now possible to have an economic windmill which can be used to generate electricity by reducing the undesirable effects of wind drag without the need for a complex and expensive rotor hub assembly.